PROJECT SUMMARY/ABSTRACT The major objective of this Academic Research Enhancement Award (AREA) R15 project is to determine the combinatory roles for environment and genetics for gene body methylation. The study of epigenetics, particularly methylation, has emphasized that chemical and physical modifications of DNA can profoundly influence how the genome is expressed and functions. The methylation of expressed regions of the genome has recently emerged as an informative genomic marker for a range of human health concerns, including cancer susceptibility, metabolic diseases, neurological function, and aging. The genomic distribution and potential function of cytosine methylation in invertebrates has accelerated through studies of non-drosophilid insects and marine invertebrates, including the model cnidarian Nematostella vectensis. Results from invertebrates strongly suggest that the distribution of methylation is highly concentrated in gene bodies (introns and exons); an observation that has transformed hypotheses about the function of methylation in physiology and environmental acclimatization. Previous research has provided snap-shots of the methylation landscape that has opened opportunities for studies of the dynamics and mechanisms of gene body methylation in response to specific physiological stressors, across generations, and over extended periods of environmental variation. Nematostella is a powerful model to address hypotheses for the roles of methylation due to its paired utility as an experimentally tractable, genome-enabled lab model and the well-characterized distribution of gene body methylation and genetic relationships of populations. The proposed research combines an integrated set of studies to characterize the capacity for epigenome regulation and its functional role in response to abiotic and biotic stressors to connect physiological and molecular acclimatization with gene body methylation (Aim 1), empirically determine the inheritance of methylation states in offspring and the specific functions for DNA methyltransferases (Aim 2), and leverage existing knowledge to determine the population structure of DNA methylation of natural environments (Aim 3). Together, the results will improve understanding of the dynamics of gene body methylation in animals, the common and unique shifts in methylation between different types of physiological stressors, and relative importance of transgenerational inheritance of epigenetic modifications for offspring encountering shared environments with parents.